This invention relates to a hollow plate-like structure which can be made into a heat storage material panel by filling therein a solidifiable heat storage material, and a process for producing a heat storage material panel by using said hollow plate-like structure which panel is easy to handle for transportation, working, etc., excellent in strength, durability and heat conductivity and usable for a variety of purposes.
Extensive studies have been made in recent years on the use of heat storage material as a means for utilization of solar energy, regeneration of waste heat or control of residential environment. Generally, there are two ways for effecting heat storage by using such a heat storage material: one way is to make use of sensible heat of the material and the other way is to utilize latent heat. A typical example of the former way comprises the use of water, crushed stone, brick, concrete or the like as heat storage material. This method, however, has several drawbacks. For example, a substantial increment in volume or weight of the heat storage material is required for increasing the amount of heat stored. Also a drop of temperature of the heat storage material itself is caused upon release of heat. This method is therefore limited in its scope of application. On the other hand, in the case of the latter way in which latent heat of the material is utilized, a typical method comprises the use of an inorganic salt hydrate or an organic crystalline material. This method takes advantage of the phenomenon of phase change by melting and solidification of the material which takes place at a given temperature. This method is advantageous in that the heat of a constant temperature can be utilized and that the portion of the system composed of the heat storage material can be reduced in size to allow a compact design because of the small temperature change of the heat storage material in accordance with storage and release of heat and the large volume of latent heat build up at the time of melting and solidification of the material.
With respect to heat storage performance and durability of the solidifiable heat storage material used in said method utilizing latent heat, the material, shape, etc., of the container used for filling the solidifiable heat storage material, as well as properties of such heat storage material, become very important factors. Such a container is required to have enough strength and durability to stand use under any environment and conditions of practical use, to have good heat conductivity to allow easy accumulation and release of heat, to provide an anticorrosive protection for the solidifiable heat storage material filled therein and to be easy to handle for transportation, working, etc., and easy to fill with the solidifiable heat storage material. Low cost is also an important requirement.
None of the hitherto available containers of solidifiable heat storage material can meet all of these requirements. In the prior art (Solar Age, May, 1983, pp. 66-69), there have been used stainless steel made cans or cylindrical containers, or plastic made cases or cylindrical containers designed to be filled with a solidifiable heat storage material in an airtight way, but all of these prior art containers involved various problems in practical use such as insufficient strength and durability, improper shape for heat transfer, difficulty in handling for transportation, working and other purposes.